How do you iterate through a hashmap?

2 years ago
William Carter
1 minute

There are several ways to traverse a HashMap.

  1. Traverse using an Iterator:
HashMap<String, Integer> hashMap = new HashMap<>();
// 添加元素到HashMap
hashMap.put("A", 1);
hashMap.put("B", 2);
hashMap.put("C", 3);

Iterator<Map.Entry<String, Integer>> iterator = hashMap.entrySet().iterator();
while (iterator.hasNext()) {
    Map.Entry<String, Integer> entry = iterator.next();
    String key = entry.getKey();
    Integer value = entry.getValue();
    // 在这里处理key和value
}
  1. Traverse using a For-Each loop:
HashMap<String, Integer> hashMap = new HashMap<>();
// 添加元素到HashMap
hashMap.put("A", 1);
hashMap.put("B", 2);
hashMap.put("C", 3);

for (Map.Entry<String, Integer> entry : hashMap.entrySet()) {
    String key = entry.getKey();
    Integer value = entry.getValue();
    // 在这里处理key和value
}
  1. Iterate through all keys.
HashMap<String, Integer> hashMap = new HashMap<>();
// 添加元素到HashMap
hashMap.put("A", 1);
hashMap.put("B", 2);
hashMap.put("C", 3);

for (String key : hashMap.keySet()) {
    Integer value = hashMap.get(key);
    // 在这里处理key和value
}
  1. Iterate through all values.
HashMap<String, Integer> hashMap = new HashMap<>();
// 添加元素到HashMap
hashMap.put("A", 1);
hashMap.put("B", 2);
hashMap.put("C", 3);

for (Integer value : hashMap.values()) {
    // 在这里处理value
}

Please choose the appropriate traversal method based on specific needs.

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